We need volunteers who can measure conductivity (a good estimator of chloride) from October 2020 to March 2021 at one of four locations along Starkweather Creek: Melvin Ct, Fair Oaks Ave, Route 30 and Ivy St.
Volunteers will receive a notification to sample within 48 hours of a prompting event (such as road salt application and warming pavement temperatures). Measurements will be taken from shores or bridges, and volunteers should only sample when they feel comfortable accessing the site. Volunteers will use test strips for chloride and a handheld meter for specific conductance. If conductivity is high, volunteers will collect water samples for chloride lab analysis and are asked to return to the site within 24 hours to collect another set of measurements.
Why is there a winter monitoring program?
When salt from parking lots, roads, and sidewalks reaches streams, chloride concentrations can become toxic. In 2013, volunteers documented 2,570 mg/L chloride in Starkweather Creek - more than three times the acutely toxic (757 mg/L) concentration! These toxic conditions pose a threat to the stream's aquatic life. Do these conditions occur after every snow melt? Where along the stream does this occur? We need a team of volunteers who can quickly sample creek conditions when chloride spikes are likely to occur so that we can better answer these questions. For winter 2020-2021, we are assembling a group of locals who are on call to sample conductivity (a good estimator of chloride) at four locations along Starkweather Creek.
What do Volunteers do?
Volunteers are assigned to one primary site and one back up site. Monitoring sites for the 2020-2021 season will be on the West Branch at Melvin Ct and Fair Oaks Ave and on the East Branch at Route 30 and Ivy St.
Volunteers will receive a notification to sample within 48 hours of a prompting event (such as road salt application and warming pavement temperatures). Measurements will be taken from shores or bridges, and volunteers should only sample when they feel comfortable accessing the site. Volunteers will use a testing strip for chloride and a handheld meter for specific conductance. If conductivity is high, volunteers will collect water samples for chloride lab analysis and are asked to return to the site within 24 hours to collect another set of measurements. Chloride spikes occur quickly, so frequent measurement is key!
How do I Become involved?
Interested in becoming a volunteer? All training and equipment will be provided - no experience necessary. Once registered, you will be contacted with more information about training, equipment, and site assignments. Volunteers are expected to be available for sampling from October 2020-March 2021.
When did conductivity spike in Jan - March 2020?
Conductivity measurements at Olbrich Gardens in early 2020 illustrate how quickly spikes in conductivity occur. Peaks in conductivity often follow snowfall and above freezing temperatures. When conductivity is above 2,000 µS/cm, chloride concentrations are estimated to be toxic (> 395 mg/L).
How will the volunteer data be used?
Conductivity is a measure of water's ability to pass an electrical current. It is affected by the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, phosphate, sodium, magnesium, calcium, iron, and aluminum. Groundwater entering Starkweather Creek carries ions from bedrock, as does surface runoff. When chloride concentrations increase, this directly increases conductivity. As a result, high conductivity measurements can be used to closely estimate chloride. As chloride concentrations decrease, other ions become more dominant in determining the creek's conductivity and predicting chloride concentrations is less accurate.
These graph show the relationship between conductivity and chloride when both were measured at the same time. Select specific points on the map to see data for those locations. The trend lines show the equation relating conductivity to chloride. At the high range (>1250 µS/cm), the relationship between conductivity and chloride is pretty linear, so conductivity measurements provide a good estimate for chloride concentrations. On the low range, the relationship between the two variables is more varied and estimating chloride using conductivity is less accurate.
Data Source: USGS, WDNR, and Public Health Madison Dane County
Volunteer conductivity measurements will be used to estimate chloride concentrations using the two linear equations on the graphs above. Volunteers will also use chloride test strips to analyze water samples. If conductivity is >2000 µS/cm, chloride is expected to reach chronically toxic concentrations (395 mg/L). When this occurs, volunteers will bottle a water sample for chloride lab analysis. The additional chloride-conductivity data pairs will be added to our existing dataset, refining the linear equations. Documenting toxic conditions will help identify when and where chloride enters Starkweather Creek and will be used to target reductions in salt use within the watershed.